There are all kinds of things you can do to those. I had the Marine 181 with larger valves, ported head, Flat top pistons. This was a screamer. I used to piss off the V8 boys all the time. I could hold the throttle at 8 grand all day long (nearly). It came from a race boat that won many trophies. The PO's son said his father paid $10,000 for all the machine work (too much to list) and the Heilborn Alcohol fuel injection that he ran on it. I ran the Clifford research 4bbl intake with a Webber 32/36DGAV carb. I regret removing and selling this engine. Speed and Power cost how much $$$ are you willing to spend? This was a 260 horse motor.
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